During induction of tumor immunity, specific thymus derived lymphocytes (T cells) recoginizing tumor antigens are stimulated to proliferate and differentiate to form the effector cells, cytotoxic lymphocytes. The cellular immune response exists concomitantly with humoral antibodies, secreted by bone marrow or bursa (birds) derived lymphocytes (B cells), which interfere with the in vitro cytotoxic activity of the killer T cells. The proposed research will be designed to study the cellular and molecular events involved in the interaction between T cells and tumor cells. The immediate goal of this investigation will be to biochemically characterize macromolecules of T cell surface involved in recognizing antigens (T cell receptor). We will then extend to the experiments for studying the interaction of mouse T cells with the allogeneic and syngeneic tumor cells. For this objective: (1) surface membrane proteins of bursectomized chicken T cells will be studied by isolating the plasma membranes and by biochemical characterization of the membrane proteins involved in the expression of the cell-mediated immunity; (2) mouse T cell surface proteins recoginizing the tumor antigens will be isolated by the methods of I125-cell surface labeling and cellular immunoadsorption and compared with chicken T cell receptors; (3) in vitro Cr51 assay system will be used for studying the effect of specific antitumor antibody on the cytotoxicity of the immune T cells; (4) the effect of chemical modification of the tumor cell surface on the vivo immune response (T vs. B cell activation).